---
description: Troubleshoot Cloudflare 1041 error code.
title: Error 1041
image: https://developers.cloudflare.com/og-docs.png
---

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# Error 1041

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-1xxx-errors/error-1041/index.md)|[Agent setup](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/agent-setup/)

## Error 1041: Invalid request rewrite (invalid header value)

This error indicates that the header value is not valid.

### Common causes

The added/modified header value is too long or it contains characters that are not allowed.

### Resolution

* Use a shorter value or expression to define the header value.
* Remove the characters that are not allowed. Refet to [Format of HTTP request header names and values](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/rules/transform/request-header-modification/reference/header-format/) in Developer Docs for more information on the allowed characters.

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